by avogadro's law the volume percent is equivalent to the mole percentage. In addition the mole percentage is equal to the pressure percentage (by dalton's law of partial pressures). Keep this in mind for the rest of this post.

I got one percent.
[tex][100.47-(101.23-.02(101.23))]/100.47[/tex]

I'm still not quite sure why they gave the molecular weight of gases in the problem, PV=nRT does not depend on mass composition. It's a colligative property

Once you find the final answer, please be considerate enough to tell the rest of us.